Better safe than sorry in my book. If they did well on 1.2, I would go with that again....especially since you are watering them thouroghly...which will more than likely release many of the nutrients that are already present in the medium directly into solution/into your plants.
At the very least I think that excess water and *too many nutes* will cause your plants to grow/stretch profusely while you are gone...especially if they are in veg mode or just entering flower.
Worst case scenario..it will jettison the nutes into your plants and fry em big time. Ya don't want that at all costs.
hope that helps.
good luck
bt dt